Printing telegraph apparatus



March 4, 1941'. H. L. KRUM 2,233,668

PRINTING TELEGRAPH APPARATUS Original Filed July 19, 1937 2 Sheets-Sheet1 FIG. 1

FIG. 2

March 4, 1941. H. 1.. KRUM 2,233,668

PRINTING TELEGRAPH APPARATUS Ofiginal Filed July 19, 1937 2 Sheets-Sheet2 HOWARD L.

| I I 84 i t I F164 Patented Mar. 4, 1941 UNITED STATES PATENT OFFICEPRINTING TELEGRAPH APPARATUS Howard L. Krum, Beverly Hills, Calif.,assignor to Teletype Corporation, Chicago, 111., a corporation ofDelaware 12 Claims.

This invention relates to printing telegraph systems and apparatus andmore particularly to two channel systems of telegraphic transmission forcontrolling telegraphic recorders.

This application is a division of application Serial No. 154,337 filedJuly 19, 1937.

An object of the invention is the provision of a relatively simpletelegraph system by utilizing two transmission channels for characterselection and printing.

Another object of the invention resides in the provision of means forcontrolling transmission of impulses over two channels of transmission,comprising two groups of transmitting elements,

' one group for each channel, and means Whereby said elements areoperative initially to impress character selecting impulses over eachchannel in staggered manner, secondly to impress printing impulsescoincidentally over said channels, and finally to impress restorationimpulses in staggered manner over each channel.

In accordance with the present invention, signal impulses aretransmitted over a two-channel or two-wire system to a printingapparatus whereat one line wire is connected through oneratchet-controlling magnet to a winding of a printing magnet, and theother line wire is connected through a second ratchet-controlling magnetto the same winding of the printing magnet. Since the printing magnet ismarginal in operation, it responds only to current appliedsimultaneously on both line wires, and character printing is effectedonly when both windings of the ratchet-controlling magnets and thewinding of the printing magnet are energized. Each character signalconsists of three parts; namely, a plurality of stepping impulses, aprolonged printing impulse, and a plurality of restoration impulses, allof which occur concurrently on both line Wires. For example, thestepping impulses occurring on one line wire control the stepping of atype wheel one thirty-sixth of a revolution per impulse, and thestepping impulses occurring on the second line wire control the steppingof the type Wheel one-sixth of a revolution per impulse. Although thesepositioning impulses exist on both line wires concurrently or existduring the same signal period but not simultaneously, the impulses onone line wire are staggered with respect to the impulses on the otherline, so as not to energize the print magnet permaturely. The maximumnumber of impulses on either line necessary to step the type wheel fromits zero or starting position to the last one of its thirty-sixpositions is'five.

The second part of the character signal consists of a prolonged impulseoccurring on both lines simultaneously and functions to operate theprinting magnet which is designed to operate in response to greatercurrent than the selecting or ratchet-controlling magnets, hence therequirement that the current on both lines simultaneously be necessaryto operate the printing magnet. The third part of the signal consists ofa series of impulses, occurring on both line wires concurrently, six oneach wire, and staggered similarly to the positioning impulses, so as toaffect only the ratchet-controlling magnets and not the printing magnet,the function of which is to effect the restoration of the type wheel toits initial or starting position. Thus, responsive to the restorationimpulses is a restoration mechanism which prevents said impulses fromrotating the type wheel further than to its zero or starting position.20

The above and other objects of the invention will be apparent from thefollowing description When taken in conjunction with the accompanyingdrawings, wherein like reference characters designate similar partsthroughout the several 25 views, and in which,

Fig. 1 is a front elevational View of a printer operable in connectionwith the transmitter according to the present invention;

Fig. 2 is a rear elevational view of the printer shown in Fig. 1;

Fig. 3 is a fragmentary sectional view taken on line 3-3 of Fig. 1;

Fig. 4 is a graphic representation of the form of signal employed by thepresent invention;

Fig. 5 is a partial plan View of a keyboard transmitter embodying theprinciples of the present invention;

Fig. 6 is a sectional view taken on line 6-6 of Fig. 5;

Fig. '7 is a view showing the series of contact cams;

Fig. 8 is a schematic electrical circuit embodying the transmitter shownin Fig. 5;

Fig. 9 is a cross-sectional view of a dial type transmitter;

Fig. 10 is a top view of the transmitter shown in Fig. 9; and

Fig. 11 is a schematic electrical circuit embodying the transmittershown in Fig. 9.

Having reference to Figs. 1 to 4, the framework of the printingapparatus co-operable with the transmitting arrangement of the presentinvention comprises a base plate ll supporting a mounting plate l2attached thereto through the instrumentality of a bar 63 bymeans ofscrews 14. A U-shaped bracket I 5 is fixed to the mounting plate 12, andtogether with the mounting plate l2 provides a journal bearing for atype wheel shaft 45, as seen in Fig. 3. Fixed to shaft It, to the rightof mounting plate l2, as viewed in Fig. 3, is a type wheel I? which hasassociated therewith a star wheel 18. Between the web of bracket 15 andmounting plate I2, shaft l6 carries thereon a sleeve i5 and a piniongear 2|, the latter pinion being fixed to the shaft l6. Inter gral withsleeve I8 is a rachet wheel 22 in which is journaled a shaft 23 whichcarries fixed thereon, planetary gears 24 and 25 disposed one on eachside of the rachet wheel 22. The planetary gear 25 meshes with thepinion 2|, and planetary gear 24 meshes with a pinion 28 which isintegral with a sleeve 2'! loosely mounted on the sleeve H]. A ratchetwheel 28 is also integral with the sleeve 2 Fixed to shaft I 5 to theleft of mounting bracket I5 (as viewed in Fig. 3) is a collar 29 whichcarries a spring post 3! (as viewed in Fig. 2) to which is connected oneend of a coiled spring 32, the other end of which is connected to a pin33 carried on a blocking segment 34 loosely mounted on shaft l6, thefunction of which will hereinafter appear.

As viewed in Fig. 2, ratchet wheel 22 has asso ciated therewith a pawl35 carried at the extremity of a pawl operating lever 36 which isassociated with an armature 31 of an electromagnet 38. -.Electro magnet38 is carried on a bracket 39 which in turn is mounted on a bracket 4|secured to the mounting plate I2. The armature 37 is pivotally supportedat 42 to bracket 39 and is biased in a clockwise direction by a spring43. Spring 43 thus normally, when magnet 38 is de-energ-ized, maintainspawl operating lever 36 against stop portion 44 of a stop bracket 45.

Ratchet wheel 28 has associated therewith a pawl 46 carried at theextremity of a pawl operating lever 4'! which is integral with thearmature 48 of an electromagnet 49. Elec-tromagnet 49 is carried on abracket 5| which is supported on a bracket 52 secured to mounting platel2. Armature 48 is pivotally supported at 53 on bracket 5i and is biasedin counterclockwise direction by a spring 54, which normally maintainspawl operating lever 41 against an adjustable stop 66.

A printing magnet 55 is supported through angle brackets 55 and 57 to aplate 58 which in turn is carried by an angle bracket 59 secured tomounting plate l2. In the present embodiment, magnet 55 is provided withtwo windings, one of which controls an armature 6| pivotally mounted at62 to th plate 58. Integral with armature 8| is a printing control lever63 near the extremity of which is secured an extension 64 which acts ona plunger 65 carried in a bracket 55 secured to mounting plate l2.Plunger 65 co-operates with a laterally disposed flange 61 integral witha print hammer 68 (Fig. 1). Flange 5! is formed with a knife-edge toco-operate with the star wheel H8, in well-known manner, to hold thetype wheel in printing position during the printing operation. The printhammer 68 is biased to its downward position by a spring 69.

The printing magnet 55 is also provided with a second winding whichcontrols an armature H pivoted at 12 to plate 58. Armatures 6| and H arebiased out of engagement with their pole faces by a common spring 13.Armature H is provided, integral therewith, with an extension 14 whichis so conformed as to avoid the pawl during the performance of therestoration function as will presently appear.

In Fig. 4 is shown a diagrammatic representation of the type of signalstransmitted by the transmitting apparatus according to the presentinvention and received over the two line wires for effecting theselective control and operation of the printer. shown in Figs. 1, 2, and3. As previously indicated, each character signal consists of threeparts; namely, the selecting or stepping impulses 8'3 and 84 comprisingthat portion indicalted as 19, the prolonged printing impulse comprisingthat portion indicated BI, and the restoration impulses 85 and 86comprising that portion indicated 82. In Fig. 4 it may be noted that theselecting impulses 83 received over one line wire are staggered withrespect to impulses 84 received over the second line wire, it beingunderstood that the number of impulses 83 or 84 vary with the characterreceived. It will also be observed that the printing impulses 8|impressed on each line wire occur simultaneously and are prolonged innature. I Following the printing impulses are the restoration impulses85 and 88 which are always, according to the present invention, six innumber and are staggered as indicated.

Impulses 83 are impressed on electromagnet 38, and as each impulse isreceived, magnet 38 becomes energized and causes its armature 31 torotate in a counterclockwise direction'against the action of spring 43,thus rotating the pawl operating lever 31 counterclockwise to raise pawl35 to engage the next preceding tooth on the periphery of ratchet 22preparatory to effecting rotation of said ratchet. Then upondeenergizaltion of magnet 38 at the termination of said impulse,armature 3'! and lever 36 are actuated in a clockwise direction by thespring 43 so that pawl 35 rotates the ratchet 22 through one angularstep. This movement of ratchet 22 causes the planetary gears 24 and 25to be carried clockwise and since, during this movement the ratchet 28is prevented from rotating, the gear 24 will be caused to rotate in aclockwise direction thus imparting the same movement to the companionplanetary gear 25. ment of planetary gear 25 causes pinion 2|, and henceItype wheel ll and star wheel l8, torotate in a counterclockwisedirection as viewed in Fig. 2 (or a. clockwise direction as viewed inFig. 1). By properly proportioning the gears involved in this gearchain, the type wheel I! is moved one angular step representative of asingle character space on the periphery of the type wheel for eachactuation of pawl 35 by magnet 38.

When a character selecting impulse 84 is received over the second linewire, it causes the energization of magnet 49, which, upon energization,attracts its armature 48 to impart clockwise rotation to the pawloperating lever 41 against the action of its spring 54 sufficiently topermit pawl 46 to engage the next preceding tooth on the ratchet wheel28. Then, upon termination of said selecting impulse, magnet, 49 becomesde-energized and spring 54 acts to rotate armature 48 and lever 41counterclockwise,

This movethus actuating pawl 46 upwardly to eifect the counterclockwiserotation of ratchet wheel 28 one angular step. Since ratchet wheel 22 isat this time held against rotation by its pawl 35, the counterclockwiserotation of ratchet whee1 28 effects, through gear 26 and planetarygears 24 and 2.5 counterclockwise rotation of pinion 2| and type wheelI1, as viewed in Fig. 2. However, instead of rotating the type wheelonly one angular step representative of a single character space, typewheel I! is rotated six angular steps or through the span of sixcharacter spaces of the periphery of the type wheel l1.

As previously mentioned character selecting impulses are transmittedover both line wires concurrently except that the impulses on one wireare staggered with respect to the other, and the number of impulsestransmitted over each line wire is determined by the character to beselected. Remembering that the type wheel is restored to an initial orstarting position prior to the selection and printing of each character,it will be assumed that the fifth character on the type wheel countingfrom the initial or starting position is to be selected. In this event,five impulses 83 will be transmitted over the first line wire (and noneover the second line wire), thus energizing magnet 38 five times androtating ratchet 22 through the angular distance of five teeth to effectthe rotation of the type wheel I! correspondingly to present the fifthcharacter on the type wheel (counting from the initial or startingposition) to the printing point. Now, in the event that it is desired toprint the eleventh character on the type wheel counting from the initialor starting position, five impulses 83 will be transmitted over thefirst line wire to actuate magnet 38 and to rotate ratchet 22 fiveangular steps, and hence type Wheel I'I five character spaces; and oneselecting impulse 84 will be transmitted over the second line wire toenergize magnet 49 to operate lever 41 to efiect the rotation of ratchet28 one angular step, in a manner previously described, to cause therotation of type wheel IT, in a single movement, six character spaceswhich, when added to the five character space movement resulting fromthe operation of magnet 38, will have caused the type wheel to be movedthrough eleven character spaces, thus presenting the eleventh character(counting from the starting position of the type wheel) to the printingpoint. It is thus seen that time has been saved in selecting theeleventh character on a type wheel by operating magnet 38 only fivetimes and magnet 49 only once, instead of operating magnet 38 eleventimes. Likewise, if magnet 49 is operated twice and magnet 38 isoperated five times, the seventeenth character will be presented to theprinting point. The latter selection will have been achieved through thetransmission of only seven impulses, instead of seventeen impulses, thusemphasizing the decided saving in line time. To select the thirtyfifthor last character on a type wheel (the thirty-sixth or zero positionbeing the blank position of the type wheel), only five impulses 83 needbe transmitted to operate magnet 38 five times, and five impulses 84need only be transmitted to operate'the magnet 49 five times. Thus, inall ten impulses have been transmitted instead of thirty-five.

After the transmission and receipt of the character selecting impulses83 and 84, the selection of the character to be printed from the typewheel has been determined, and following the receipt of these selectingimpulses 83 and M a prolonged printing impulse 93 is transmitted overboth line wires simultaneously, thus energizing the print magnet 55,causing armature 6| thereof to be attracted and printing arm 63 to beactuated in a counterclockwise direction against the action of spring 13to impart, through portion 64, upward movement to plunger 65, whichthrough lateral portion 6'! imparts counterclockwise movement (as viewedin Fig. 1) to printing hammer 69, thus throwing the pallet portion ofthe printing arm 68 against the type wheel l'l. At the same time theknife-edge of portion 61 co-operates with the star wheel IE to preventmovement of the type wheel l'l during the performance of the printingfunction.

The tape 8'! is directed in tape guide 88 through the printing area.Engaging tape 81 through a slot (not shown) in the tape guide 88 is atape spacing roller 89 which is provided, as is common practice, with aknurled periphery and which, to effect movement of the tape, cooperateswith a pressure roller 9! carried on a lever 92 which is spring biasedin a counterclockwise direction (as viewed in Fig. 1) by a spring 93.Roller 89 is mounted on a shaft 94 (Fig. 2) to which is also fixed aspacing ratchet 95. Co-operating with spacing ratchet 95 is a pawl 96which is carried at the extremity of the printing lever 63. Thus, uponeach operation of lever 63 in response to the printing impulse 8|, thepawl 96 is reciprocated thereby engaging the next tooth on the ratchet95 and upon a downward movement of pawl 96, ratchet 95 is rotated oneangular step in a clockwise direction (as viewed in Fig. 2) thus causingroller 89 to be rotated one angular step in a counterclockwise direction(as viewed in Fig. 1). A detent spring 91 is provided to prevent backspacing of the ratchet wheel 95 during the performance of the spacingoperation. Associated with the type wheel H, as viewed in Fig. 1, is aninking roller 98 carried on a lever 99 biased by a spring I00.

As previously indicated, the third part of each character signalcomprises a plurality of impulses over each line wire, sumcient innumber i to insure the stepping of the type wheel forward (in the samedirection as for character selection) to its starting or zero position.Since six impulses transmitted over each line wire is sufficient torotate the type wheel a complete revolution, this number of impulses oneach line has been chosen to effect restoration. Of course, the

extent to which it is necessary to rotate the type wheel to its zeroposition after the selection of a character varies with the characterselected. Therefore, it is necessary to provide mechanism to preventrotation of the type wheel farther than to its zero position. To achievethis result in connection with the six-step magnet 49, the segment 34and arm 11 are provided, and in connection with the one-step magnet 38,the pins 16 and arm M are provided.

The magnets 38, 49, and are connected in the manner shown in Fig. 8wherein the magnet 38 is included in one line wire 3M and the magnet 49is included in the other line wire 3l5, magnet 55 being connected toboth line wires so that impulses transmitted over line wire 314 willpass through magnet 38 thence through magnet 55 to ground. In the formof the invention shown in Fig. 2, the magnet 55 is provided with twowindings, one of which is margial in character (and controls armatureBl) so that the impulses transmitted over only one of the line till thepath of edge 10].

wires will not energize the marginal winding of the magnet. On theotherhand, it requires the total current on the two wires to effect theenergization of said marginal Winding of magnet 55- Magnet 55 is alsoprovided with a second winding which responds to the selecting andrestoration impulses over either wire to cause the operation of armature-1I.

Now, when the restoration impulses 85fare transmitted over line wire 3|4, they will pass through magnet 38 and also the second mentionedwinding of magnet 55. The effect of restoration impulses 85 on magnet 38will be to operate arm 36 and pawl 35 to cause the clockwise rotation ofratchet wheel 22. However, since these restoration impulses also passthrough the second mentioned winding of magnet 55, armature 1| isoperated to rotate lever 14 clockwise to bring hook portion 15 into thepath of pins 16. Thus, pawl 35 will continue to actuate ratchet wheel22, in response to the restoration impulses 35, only until one of thepins 16 is intercepted by the hook portion 15 after which the remainingrestoration impulses 85, if any, will have no eifect. During thecharacter selecting operation, the actuation of arm 14, and hence 'hookportion 15, in response to impulses 83 and 84, will have no arrestingeffect on the ratchet wheel 22, for the reason that the maximum distancethat ratchet 22 may be rotated during a character selecting cycle isfive steps, which is less than the number of steps between successivepins 16.

Similarly, the restoration impulses 86 transmitted over line wire 3l5will pass through magnet 49 and said second winding of magnet 55. Theeffect of staggering impulses 85 and 86 is to maintain lever 14 steadilyin its clockwise position, thus giving the effect of a continuouscurrent on the second winding of magnet 55. The reception of therestoration impulses 86 by magnet 49 will cause lever 41 and pawl 46 torotate ratchet wheel 28 step by step in a counterclockwise direction. Aspreviously described, lever 41 is provided with a vertically extendingarm 11 having a laterally extending portion 18. Thus, as lever 41 isoscillated, the portion 18 is reciprocated vertically. Portion 18 isthus free to reciprocate vertically until the segment 34 is presented inits path, whereupon oscillation of lever 41 is prevented. In thismanner, type wheel [1, during the restoration operation, can be moved insix-step or six-character-space intervals until segment 34 is presentedbeneath the portion 18, after which the remaining restoration impulses,if any, will have no effect upon lever 41. The mechanism is so designedthat when a pin 16 is intercepted by hook portion 15, and the portion 18is intercepted simultaneously therewith by segment 34, the type wheel l1will have reached its zero or starting position with the blank portiononthe periphery of the type wheel presented to the printing point.

Segment 34, as previously described, is yieldably connected to shaft l6by means of coil spring 32. The purpose of this is to prevent segment 34during the character selection operation, from binding against thelateral portion 18; that is, assuming that segment 34 during characterselection is presented with its forward edge l0! just to the right ofthe vertical path of portion 18, the lever 41 in response to a selectingimpulse will be actuated in a clockwise manner,'thus bringing portion 18downwardly into Then on its upward move- ,latches 306. initiatedsubstantially simultaneously with the menrt, lever 41 willactuate'ratchet wheel 28 to cause its counterclockwise rotation.However, before ratchet wheel 28 has advanced very far, edge l0l willimpinge against portion 18 which has not yet escaped the segment 34.Without the yieldable spring connection between segment 34 and shaft I6,the pressure of pawl 46 against ratchet wheel 28 by means of spring 54would cause segment 34 to'bind against portion 18, thus possiblyinjuring the mechanism. To compensate for this, segment 34 is permittedto yield and pawl 46 is permitted to complete its action upon ratchetwheel 28, whereafter when portion 18 clears the segment 34, segment 34'will be biasedby spring 32 to its normal counterclockwise position. v

I Transmitting mechanism In Figs. 5 to 11, inclusive, are shown variousforms of transmitters and circuits therefor which may be employed inconnection with the receiving printer shown in Figs. Ito 3. In Figs. 5to 7, inclusive, is illustrated a. keyboard transmitter of the typeshown and disclosed in United States Patent No. 1,595,472. As shown inFigs. 5 and 6 the keyboard portion, indicated generally as 30!, isprovided with a set of keys 302 arranged similarly to the well-knowntypewriter keyboard, and, as illustrated in Fig. 5, key levers 303associated with the keys 302 are pivotally mounted on a common shaft 304and are spring held in normal horizontal position by individual springs(not shown). Arranged transversely below the key levers 303 (Fig. 6), inoperative relation thereto, are a series of 'V-notched selector bars 305which are adapted to be operated permutably, in well-known manner, inaccordance with the key depressecL' The selector bars 305 are pivotallyarticulated to a corresponding series of locking latches 306 which areadapted to be rocked to either of two positions thereby. Associated withlatches 306 is a corresponding series of contact levers 301 for makingand breaking. contacts 308. Contact levers 301 co-operate withindividual contact cams 309 mounted on shaft 3| I. The shaft 3 isprovided with a single revolution clutch mechanism (not shown) which iscontrolled by a universal bar member as set forth in Patent No.1,595,472. 1

The operation of the transmitting unit 'con- 'sists essentially in thedepression of a key lever 303 which effects the arrangement of the setof selector bars 305 periodically in accordance with a predeterminedcode combination, thesetting of which determines the position of thelocking The rotation of the cams 309 is setting of the locking latches306, and a locking loop 3|2 controlled by a cam 3I3 is permitted torotate in a counterclockwise direction (Fig; 6) to effect the locking oflatches 306. The setting of the locking latches 306 determines whetherthe contact levers 301 shall or shall not be affected by theirassociated cams 309 to cause the opening or closing of. their associatedcontacts 308 to transmit over a signal line (as will appear presentlyfrom a description of Fig.8) to the receiving station apredetermin'edcombination of signaling impulses. The respective notches in the cams309 are arranged in a spiral progression so that upon the rotation ofthe cam assembly, the contacts 308 will be controlled suecessively.

In the present form of transmitter,-the' contact cams 309 are eight'innumber and are divided in, groups of four each, each group of fourbeingconnected to a separate line wire over a two-wire telegraph-system.In Fig. 7 is shown the series of eight contact cams 303 with their.respective contact levers and contacts. In this illustration, contactcams 32!, 322, 323, and 32 comprise one group, the contacts 358 of whichare connected Over line wire 3! 4 of Fig, 8, and contact earns 33!, 332,333, and 334 comprise a second group, the contacts 308 of which areconnected over a second line wire 3!5 of Fig. 8. It will be noted thatcontact cams 32! and 33! are provided with a single depression inresponse to which a single impulse is transmitted through a contact 308for each revolution of the cam. It will be noted further that cams 322and 323 and cams 332 and 333 are each provided with two adjacent notchesso that for each revolution of these-cams, two impulses will betransmitted. Then to enablethe sending of one to five character impulsesover each wire 3! and 315, the cams in each group may be selected inproper combinations; for example, to send a single impulse over line3I4, cam 32! only would be perated. To transmit two impulses over line3M, cam 322 or cam 323 will be operated. To send three impulses overline 3M, cam 32! would be operated simultaneously with cam 322 or 323.To send'four impulses over line 3|4, cams 322 and 323 would be operatedsimultaneously, and to transmit five signals over the line all of theearns 32!, 322, and 323 would be operated simultaneously. The samepermutable operation of the second group of cams 33!, 332, and 333' iseffected to transmit signals over line 3!.5. It will be observed thatthe notches of each group of cams arearranged in a progressive manner.

Cams 324' and 334 are not controlled by. lock latches 336 and arepermitted to rotate invariably for every operation of transmitting shaft31!. Each of the cams 324 and 334 isso cut as to transmit (following thecharacter selecting impulses) first the prolonged printing impulse andthereafter-six restoration impulses.

Having reference to Fig. 8 there is shown a circuit diagram for a twowire telegraph system employing the transmitter shown in Figs. 5 to 7and printers according to Figs. 1 to 3; for example, herein described.According to this system, impulses in accordance with the diagram shownin Fig. 4 are transmitted, from battery 335, through contacts 338, overline wires 3M and M5, through their respective stepping magnets 38 and49, thencethrough printing magnet 55 to ground.

In Figs. 9 to 11 is shown a dial type of transmitter. In accordance withthis form of transmitter, a series of dialing keys 35! are disposedabove a casing 352, and integral with each dialing key is a key lever353 loosely carried upon a shaft 354. Each of the key levers 353 isprovided with oppositely directed arcuately shaped arms 355 and 356, theupper arcuate edges of which are notched in code manner. Associated withthe arm 355 of each of the key levers 353 is a pin351 carried on acommon rod 353 suitably journaled in the casing 352. There is alsocarried on the rod 358 a contact operating pin 359 which co-operateswith the upper blade 35! of contact 332. The assembly comprising rod 353and pins 35'! and 359 are biased in their clockwise direction (as viewedin Fig. 9) by a spring 363. When a key lever 353 is rotated in acounterclockwise direction, the code projections on the arm 355 rock therod 358 repeatedly in a clockwise direction and rotate arm 353 away fromthe contact 33!. Then, upon the return of key lever 353 to its rightwardor clockwise position (as shown in Fig. 9), the code projections on arm355 will again rock rod 353 repeatedly in a counterclockwise directionagainst the action of spring 353 to close the contact 352 intermittentlyto transmit impulses over the line wire, as will be hereinafterexplained.

Similarly there is associated with the arm 353 of eachof the key levers353 a pin 354 which is carried upon a common rod 365. There is alsofixed to rod 335 a contact operating pin 355 which operates a contact361. As a key lever is rotated counterclockwise, the code projectionsupon arm 353 act, through pins 355, to rock rod 335 repeatedly in aclockwise direction and rotate arm 363 away from contact 331. Then, uponreturn of the key lever 363 to its clockwise position, the code notcheson arm 355 act to rock rod 355 repeatedly in a counterclockwisedirection against the action of its spring 358 to close contact 36'!intermittently to transmit signal impulses over a second line wire.

According to the presently described form of the invention, means isprovided for preventing the operation of more than one key lever 353 ata time; that is, whenone key lever 353 is operated, all of the remainingkey levers are locked against operation. To achieve this result, an arm339 is associated with each key lever whicharms 339 are fixed to theshaft 354. Pivotally carried on key lever 353 adjacent the outerextremity of arm 359 is a bell crank lever 31!. There is also carried onkey lever 353 a bell crank lever 312, and bell cranks 31! and 312 arebiased attrahently by a common spring 313. Extending longitudinallythrough the casing 352- and supported therein is a rod 31 whichcooperates with bell cranks 31! and 312. Also fixed to the shaft 354 isan arm' 315 to the extremity of which is connected one end of a spring315, the other of which is anchored to the casing 352. Thus, in thismanner, all of the arms 3% are biased to their clockwise positionagainst a stop 311 carried on each of the key levers 353.

When the arms 359 assume their clockwise position against stops 311,their ends 318 thereof also bear against bell cranks 312 to rotate thelatter sufiiciently to remain disengaged from bar 313 as indicated inFig. 9. Also, when key lever 333 is held in its clockwise position, bellcrank lever 31! bears against bar 314 in such a manner as to maintainits horizontal arm disengaged from end 318 of arm 3%.

Now, when a key lever 353 is operated by means of its associated dial ngkey 35!, and is thereupon actuated in a counterclockwise direction, itspin 31'! engages arm 353 and carries said arm forwardly therewith. Thisaction is rendered possible because arm 339 is still bearing againstbell crank 312 to hold said bell crank disengaged from bar 314, and aslever 353 is moved counterclockwise, bell crank 312 passes under the bar315. Since all of the arms 363 are fixed to shaft 354, the remainingarms 359 will be moved independently of their associated key levers 353.Then, because of this operation of arm 333 independently of key levers353, bell cranks 312 of all but the operated key lever 353 will be freeto be actuated by their respective springs 3'13, so as to bring thehorizontal arms of hell cranks 312 into latching engagement with bar314. Therefore, so long as arms 339 of all but the operated key lever353 remainout of contact with their respective bell cranks 312, all ofthe remaining key levers 353 are locked against operation. In Fig. 10 isshown a plan view of the dial transmitter with a part broken away toshow the contact 362.

In Fig. 11 is shown a circuit diagram of a two wire telegraph systememploying the dial transmitter shown in Figs. 9 and 10. In this systemthe contact 362 is operated intermittently in accordance with the codenotches on the arm 355 of a key lever 353 to transmit impulses over thefirst line wire 319 through a stepping magnet 38! and print magnet 382to ground. Similarly, contact 361 is operated intermittently in responseto the code notches on the arm 356 of a key lever 353 to transmit over asecond line wire 383 signal impulses to a stepping magnet 384 thencethrough the print magnet 382 to ground. Since print magnet 382 is ofmarginal operation, it will not respond to impulses received over eitherline wire singly but only when a printing impulse is received over bothline wires 379 and 383 simultaneously. It is understood that the codenotches on arms 355 and 356 may comprise the character signalingimpulses, the printing impulse, and restoration impulses in accordancewith the signal indicated in Fig. 4.

Although the present invention has been disclosed in connection withcertain specific embodiments thereof, it is understood that suchembodiments are merely illustrative and not restrictive, and that allforms coming within the scope of equivalency of the appended claims areintended to be covered by the invention.

What is claimed is:

1. In a telegraph transmitter, means for controlling transmission ofimpulses over two channels of transmission, comprising two groups oftransmitting elements, one group for each channel, and means wherebysaid elements are operative initially to impress character selectingimpulses over each channel in staggered manner, secondly to impressprinting impulses coincidentally over said channels, and finally toimpress restoration impulses in staggered manner over each channel.

2. In a dial transmitter for transmitting signals over two transmissionchannels, a plurality of dialing keys, a pair of coded arms carried oneach key, a pair of contacts, one included in each channel, and contactcontrolling means for each contact co-o'peratively associated withcorresponding arms of said pairs of arms.

3. In a dial transmitter for transmitting signals over two transmissionchannels, a plurality of dialing keys, a pair of coded arms carried oneach key, a pair of contacts, one included in each channel, contactcontrolling means for each contact co-operatively associated withcorresponding arms of said pairs of arms, and

means controlled by each key for locking, during each actuation thereof,the remaining keys against operation.

4. In a. dial transmitter for transmitting signals over two transmissionchannels, a plurality of dialing keys, a pair of coded arms carried oneach key, a pair of contacts, one included in each channel, and contactcontrolling means for each contact co-operatively associated withcorresponding arms of said pairs of arms and effective to transmit oversaid channels concurrently signals in accordance with the codes on saidarms.

5. In a dial transmitter for transmitting signals over two transmissionchannels, a plurality of dialing keys carried loosely on a common shaft,a pair of coded projections carried on each key, a pair of contacts, oneincluded in each channel, contact controlling means for each contactco-operatively associated with corresponding projections of said pair ofprojections, an-

terlocked therewith to actuate thereby all said' arms simultaneously torender the locking means of the remaining keys effective to lock saidremaining keys against operation.

6. In an apparatus for transmitting signals over two transmissionchannels, a series of contacts, a permutation code selector mechanism,two groups of contact controlling mechanisms, one group for eachchannel, and means whereby said mechanisms are controlled permutably bysaid selectormechanism and are operative in a single cycle to impressconcurrently signal impulses over each channel in staggered manner,followed invariably by a printing impulse occurring coincidentally oneach channel and a definite series of restoration impulses occurring oneach channel in staggered manner.

'7. In a keying device, a shaft, a plurality of keys carried loosely onsaid shaft, an arm asso ciated with each key and fixed to said shaft,locking means carried by each key and controlled by saidarms, and meanseffective upon each actuation of a key whereby the arm associated withthe actuated key is interlocked therewith to actuate therebyall saidarms simultaneously,

to render the locking means of the remaining keys effective to lock saidremaining keys against operation.

8. In a keying device, a shaft, a plurality of keys carried loosely onsaid shaft, an arm associated with each key and fixed to said shaft, alock bar, dual bell crank locking means carried by each key andco-operable with said lock bar and controlled by said arms. andmeanseifective upon each actuation of a key whereby the arm,

associated with the actuated key is interlocked therewith to insurecontrol of said shaft by said key lever and simultaneously'to render thelocking means of the remaining keys effective to lock said remainingkeys against operation.

9. In a keying device, a shaft, a plurality of keys carried loosely onsaid shaft, an arm associated with each key and fixed to said shaft, a

lock bar,.dual bell crank locking means carried by each key andco-operable with said lock bar and controlled by said arms, and meanseffective upon each actuation of a key whereby the arm associated withthe actuated key is interlocked therewith through the instrumentality ofone of said bell cranks to insure control of said shaft by said keylever and simultaneously to render the locking means of the remainingkeys elfective, through the other of said bell cranks, to lock saidremaining keys against operation.

10. In a dial transmitter for transmitting signals over two channels, ashaft, a plurality of dialing keys loosely mounted on said shaft, a pairof coded arms on each key, an arm associated with each key and fixed tosaid shaft, a pair of contacts, one included in each channel, contactcontrolling means for each contact cooperatively associated withcorresponding arms of said pairs of arms, locking means carried by eachkey and controlled by said arms, and means effective upon each actuationof a key whereby the arm associated with the actuated key is interlockedtherewith to actuate thereby all said arms simultaneously to render thelocking means of the remaining keys effective to lock said remainingkeys against operation.

11. In a dial transmitter for transmitting signals over two channels, ashaft, a plurality of dialing keys loosely mounted on said shaft, a pairof coded arms on each key, an arm associated with each key and fixed tosaid shaft, a pair of contacts, one included in each channel, contactcontrolling means for each contact cooperatively associated withcorresponding arms of said pairs of arms, a lock bar, dual bell cranklocking means carried by each key and cooperable with said lock bar andcontrolled by said arms, and means effective upon each actuation of akey whereby the arm associated with the actuated key is interlockedtherewith to insure control of said shaft by said key lever andsimultaneously to render the locking means of the remaining keyseffective to lock said remaining keys against operation.

12. In a dial transmitter for transmitting signals over two channels, ashaft, a plurality of dialing keys loosely mounted on said shaft, a pairof coded arms on each key, an arm associated with each key and fixed tosaid shaft, a pair of contacts, one included in each channel, contactcontrolling means for each contact cooperatively associated withcorresponding arms of said pairs of arms, a lock bar, dual bell cranklocking means carried by each key and cooperable with said lock bar andcontrolled by said arms, and means effective upon each actuation of akey whereby the arm associated with the actuated key is interlockedtherewith through the instrumentality of one of said bell cranks toinsure control of said shaft by said key lever and simultaneously torender the locking means of the remaining keys efiective, through theother of said bell cranks, to lock said remaining keys againstoperation.

HOWARD L. KRUM.

